Conjunction search revisited.

Abstract

Search for conjunctions of highly discriminable features can be rapid or even parallel. This article explores, three possible accounts based on (a) perceptual segregation, (b) conjunction detectors, and (c) inhibition controlled separately by two or more distractor features. Search rates for conjunctions of color, size, orientation, and direction of motion correlated closely with an independent measure of perceptual segregation. However, they appeared unrelated to the physiology of single-unit responses. Each dimension contributed additively to conjunction search rates, suggesting that each was checked independently of the others. Unknown targets appear to be found only by serial search for each in turn. Searching through 4 sets of distractors was slower than searching through 2. The results suggest a modification of feature integration theory, in which attention is controlled not only by a unitary "window" but also by a form of feature-based inhibition. Objects in the real world vary in a large number of properties, at least some of which appear to be coded by specialized, independent channels or modules in the perceptual system (

Task-Dependent Learning of Attention

“…However, these studies claim different human performances in conjunction search. The experiments done by Wolfe et al (1989) and Treisman and Sato (1990) suggest that the standard conjunction target is detected in parallel. Quinlan and Humphreys (1987), on the other hand, state that subjects perform a serial search to detect the target.…”

“…, the time needed to move attention from the current location to the new position. Based on values extracted from psychological experiments (Treisman and Sato, 1990;Wolfe et al, 1989), the initial response time has been set to 300 ms and the duration of a shift of attention has been set to 60 ms. With these definitions, the model's reaction time is defined as…”

“…A visual search paradigm that is often used (Quinlan and Humphreys, 1987;Treisman and Sato, 1990;Wolfe et al, 1989) is feature and conjunction search. In a feature search task the target differs in one and the same feature from all distractors.…”

“…All studies on feature and conjunction search (Quinlan and Humphreys, 1987;Treisman and Sato, 1990;Wolfe et al , 1989) report that in feature search the target is detected in parallel. However, these studies claim different human performances in conjunction search.…”

“…The second simulation is based on an experiment conducted by Treisman and Sato (1990), in which the impact of top-down information can be manipulated. In this experiment for each subject a pair of maximally contrasting distractors is randomly chosen.…”